This invention generally relates to medical devices for manipulating matter in a body. More particularly, the invention relates to a medical device including an object-engaging unit, such as a retrieval device or a surgical blade, and a sheath for introduction of the object-engaging unit directly into a body opening or cavity or into a body through an endoscope or a laparoscope channel, for example.
Medical devices can be used in a body opening, cavity, or tract to manipulate material within the body. Such medical devices may be used through an endoscope or a laparoscope. When inserted into a flexible endoscope, medical devices impair the ability of the flexible endoscope to achieve the desired flexion needed to engage material at a remote body site.
One such medical device has a sheath and an object-engaging unit, such as a basket, that is moveable relative to the sheath from a collapsed state within the sheath to another state in which the unit extends past the distal end of the sheath. Typically, the object-engaging unit is in an operational mode when the object-engaging unit is extended beyond the distal end of the sheath. The sheath typically extends from a handle, located at the proximal end (i.e., the end away from the patient) of the sheath, to the object-engaging unit, which is located at the distal end of the sheath (i.e., the end near the patient and that goes into the patient).
One purpose of the sheath is to collapse and release the object-engaging unit by sliding the sheath over (to collapse) or away from (to release) the object-engaging unit, or by moving the object-engaging unit into (to collapse) and out of (to release) the sheath. The object-engaging unit is, for example, a grasping forcep-like assembly, a basket assembly, or any type of tissue and/or object manipulating, capturing, and/or retrieving assembly. When the object-engaging unit is enclosed within the sheath, the object-engaging unit is inoperative and in its collapsed or withdrawn state. For example, object-engaging units, such as baskets, assume a collapsed, reduced diameter profile when the basket is enclosed within the distal end of the sheath. When the sheath is retracted relative to the basket or the basket is extended beyond the distal end of the sheath, the basket expands to a relatively larger diameter than when the basket is enclosed and collapsed within the sheath. In the expanded position, the basket is positioned and is operable at least to capture material in the body, such as kidney stones. If the object-engaging unit is, for example, a blade, it would be withdrawn when not needed to cut, and then extended at least partially out beyond the distal end of the sheath to allow cutting with the blade. The sheath also serves other purposes. For example, the sheath serves to encompass and protect the object-engaging unit as it is inserted into the body cavity or channel of an endoscope. The sheath also serves to protect the body cavity from damage that may be introduced by the object-engaging unit itself if it were released, expanded, or extended during passage of the sheath into the body. Also, the sheath must provide sufficient strength and rigidity to allow its insertion into the body or endoscope channel while also providing sufficient flexibility to permit the sheath to navigate through the tortuous channels of the body cavity, opening, or tract.
It is an object of the invention to provide a medical device comprising a sheath with sufficient flexibility to locate and engage material at a site in a body, such as the renal pelvis. That is, the sheath is sufficiently flexible to navigate the turns and curves of the body tract into which the medical device is introduced in order to manipulate target material at the remote body site. The sheath is also sufficiently flexible to allow a flexible endoscope, into which the sheath is inserted, to achieve the desired flexion.
It is another object of the invention to provide a medical device including a sheath that has sufficient strength at the proximal and distal end portions of the sheath to locate, engage, and retrieve target material at a remote body site, and to actuate an object-engaging unit without distorting or deforming the distal end portion of the sheath.
It is yet another object of the invention to provide a method of using medical devices including such sheaths to retrieve material at a remote site in a body.
In one aspect, the invention relates to a device for use in manipulating material at a site within a body. The device includes a handle and a sheath extending from the handle. The sheath includes a lumen, a proximal end, a distal end, a proximal portion, an intermediate portion, and a distal portion. The intermediate portion of the sheath is more flexible than both the proximal portion and the distal portion of the sheath. The device also includes an object-engaging unit. The object-engaging unit and the sheath are moveable relative to each other to achieve a collapsed state of the object-engaging unit in which the object-engaging unit is collapsed within the lumen of the distal portion of the sheath, and another state in which the object-engaging unit extends from the distal end of the sheath.
In one embodiment of the device according to this aspect of the invention, the outside diameter of the intermediate sheath portion is more narrow than the outside diameter of the proximal and distal sheath portions. The intermediate sheath portion, in another embodiment, has one or more fewer layers than the proximal and distal sheath portions, and in this case the outside diameter of the intermediate sheath portion may or may not have the same outside diameter as the proximal and distal sheath portions.
Also in accordance with the invention, the intermediate sheath portion has at least two sections, and at least one of the sections has a different number of layers of material than at least one other of the sections. The sections can be arranged in a variety of different patterns such as circumferential, longitudinal, spiral, helical, and/or criss-cross patterns.
Also, in accordance with this aspect of the invention, the layers of the sheath in all portions of the sheath comprise various materials, such as fluorinated ethylenepropylene (FEP), polytetrafluoroethylene (PTFE), stainless steel braid, or polyimide. Regardless of the materials or the number of layers of material used to make the proximal, intermediate, and distal sheath portions, the diameter of the sheath lumen is the same or different in the proximal, intermediate, and distal sheath portions.
In another aspect, the invention relates to a sheath for a medical device, wherein the sheath comprises a wall extending from a proximal end of the sheath to a distal end of the sheath. The wall defines a lumen extending from the proximal sheath end to the distal sheath end. The wall includes a proximal portion, an intermediate portion, and a distal portion. The intermediate portion is more flexible than the proximal and distal portions. The lumen in the distal portion of the sheath wall is adapted for receiving an object-engaging unit.
In still other aspects of the invention, methods of manipulating material in a body include inserting into a body (either directly or through some other mechanism such as an endoscope channel) a medical device including a sheath of the type described above. The steps of the methods include moving the object-engaging unit from a collapsed state to another state in which the object-engaging unit is extended beyond the distal end of the sheath, engaging the material in the body, and ultimately withdrawing the device from the body.